1. Field of the Invention
The present invention concerns a tape transporting device used for transporting a magnetic tape. More specifically, the present invention concerns a tape transporting device used for transporting an endless loop magnetic tape.
2. Description of the Prior Art
As a technique for efficiently duplicating a large quantity of a video tape on which video signals have been recorded or a tape on which pulse code modulation (PCM) signals have been recorded, a transfer technique wherein an unrecorded copy tape is aligned with a master tape on which signals have preliminarily been recorded and a magnetic field or heat is impressed on the interface between the two tapes for the purpose of transferring the signals has been developed. Numerous conventional tape transporting devices have been developed for transporting the master tape and copy tape in the aforementioned transfer duplication technique. A representative example of a tape transporting device is shown in U.S. Pat. No. 4,213,159. In this device, front and rear ends of a master tape are connected to one another, and the master tape is used as a so-called "endless loop." In other words, a long and winding master tape is partially stored in a loop bin, and the tape is partially outside of the loop bin. An extremely narrow slit is formed at an outlet of the loop bin in such a way that the master tape will not be entangled when it is retrieved from the loop bin.
One important problem of the aforementioned conventional tape transporting device is that the transporting of the master tape stored in the loop bin through the bin outlet is unstable.
In other words, since a long and winding master tape is stored in the loop bin, virtually no tension is applied to the master tape when it is retrieved from the loop bin.
As a result, it is difficult to impress tension on the master tape even if the master tape is retrieved from a slit, and it is impossible to attain a high tape transporting stability. In prior art devices, if the master tape transporting speed increases, the master tape cannot be smoothly removed from the loop bin, and as a result, the master tape is easily damaged.
The present invention improves the transporting stability of a master tape which is stored in a loop bin as an endless loop.